Test::Group allows for grouping together related tests in a standard
Test::More-style script.  It provides a bunch of maintainability and
scalability advantages to large test suites:

 * related tests can be grouped and given a name.  The intent of the
   test author is therefore made explicit with much less effort than
   would be needed to name all the individual tests;
 * the test output is much shorter and more readable: only failed
   subtests show a diagnostic, while test groups with no problems inside
   produce a single friendly ok line;
 * no more tedious test counting: running an arbitrarily large or
   variable number of tests (e.g. in loops) is now hassle-free and
   doesn't clutter the test output.
